Ink jet printhead with glass nozzle chambers

ABSTRACT

An ink jet printhead is provided. The printhead comprises: a silicon substrate; a CMOS layer comprising drive and control circuitry, the CMOS layer being formed on the silicon substrate; a passivation layer covering the CMOS layer; and a plurality of nozzles mounted on the passivation layer. Each nozzle comprises a chamber adapted to contain an ejectable liquid; and a droplet ejection actuator associated with each of the chambers respectively, the droplet ejection actuator being electrically connected to the drive circuitry and adapted to eject a droplet of the ejectable liquid from the nozzle. The chambers are comprised of a glass material.

CROSS REFERENCES TO RELATED APPLICATIONS

The present application is a continuation of U.S. application Ser. No.10/407,212 filed on Apr. 7, 2003, now issued as U.S. Pat. No. 7,416,280,which is a continuation-in-part of U.S. application Ser. No. 09/113,122filed on Jul. 10, 1998, now issued as U.S. Pat. No. 6,557,977, theentire contents of which are herein incorporated by reference.

The following Australian provisional patent applications are herebyincorporated by reference. For the purposes of location andidentification, US patents/patent applications identified by their USpatent/patent application serial numbers are listed alongside theAustralian applications from which the US patents/patent applicationsclaim the right of priority.

US PATENT/PATENT CROSS-REFERENCED APPLICATION (CLAIMING AUSTRALIAN RIGHTOF PRIORITY FROM PROVISIONAL PATENT AUSTRALIAN PROVISIONAL DOCKETAPPLICATION NO. APPLICATION) NO. PO7991 09/113,060 ART01 PO85056,476,863 ART02 PO7988 09/113,073 ART03 PO9395 6,322,181 ART04 PO801709/112,747 ART06 PO8014 6,227,648 ART07 PO8025 09/112,750 ART08 PO803209/112,746 ART09 PO7999 09/112,743 ART10 PO7998 09/112,742 ART11 PO803109/112,741 ART12 PO8030 6,196,541 ART13 PO7997 6,195,150 ART15 PO79796,362,868 ART16 PO8015 09/112,738 ART17 PO7978 09/113,067 ART18 PO79826,431,669 ART19 PO7989 6,362,869 ART20 PO8019 6,472,052 ART21 PO79806,356,715 ART22 PO8018 09/112,777 ART24 PO7938 09/113,224 ART25 PO80166,366,693 ART26 PO8024 6,329,990 ART27 PO7940 09/113,072 ART28 PO79396,459,495 ART29 PO8501 6,137,500 ART30 PO8500 09/112,796 ART31 PO798709/113,071 ART32 PO8022 6,398,328 ART33 PO8497 09/113,090 ART34 PO80206,431,704 ART38 PO8023 09/113,222 ART39 PO8504 09/112,786 ART42 PO80006,415,054 ART43 PO7977 09/112,782 ART44 PO7934 09/113,056 ART45 PO799009/113,059 ART46 PO8499 6,486,886 ART47 PO8502 6,381,361 ART48 PO79816,317,192 ART50 PO7986 09/113,057 ART51 PO7983 09/113,054 ART52 PO802609/112,752 ART53 PO8027 09/112,759 ART54 PO8028 09/112,757 ART56 PO93946,357,135 ART57 PO9396 09/113,107 ART58 PO9397 6,271,931 ART59 PO93986,353,772 ART60 PO9399 6,106,147 ART61 PO9400 09/112,790 ART62 PO94016,304,291 ART63 PO9402 09/112,788 ART64 PO9403 6,305,770 ART65 PO94056,289,262 ART66 PP0959 6,315,200 ART68 PP1397 6,217,165 ART69 PP237009/112,781 DOT01 PP2371 09/113,052 DOT02 PO8003 6,350,023 Fluid01 PO80056,318,849 Fluid02 PO9404 09/113,101 Fluid03 PO8066 6,227,652 IJ01 PO80726,213,588 IJ02 PO8040 6,213,589 IJ03 PO8071 6,231,163 IJ04 PO80476,247,795 IJ05 PO8035 6,394,581 IJ06 PO8044 6,244,691 IJ07 PO80636,257,704 IJ08 PO8057 6,416,168 IJ09 PO8056 6,220,694 IJ10 PO80696,257,705 IJ11 PO8049 6,247,794 IJ12 PO8036 6,234,610 IJ13 PO80486,247,793 IJ14 PO8070 6,264,306 IJ15 PO8067 6,241,342 IJ16 PO80016,247,792 IJ17 PO8038 6,264,307 IJ18 PO8033 6,254,220 IJ19 PO80026,234,611 IJ20 PO8068 6,302,528 IJ21 PO8062 6,283,582 IJ22 PO80346,239,821 IJ23 PO8039 6,338,547 IJ24 PO8041 6,247,796 IJ25 PO800409/113,122 IJ26 PO8037 6,390,603 IJ27 PO8043 6,362,843 IJ28 PO80426,293,653 IJ29 PO8064 6,312,107 IJ30 PO9389 6,227,653 IJ31 PO93916,234,609 IJ32 PP0888 6,238,040 IJ33 PP0891 6,188,415 IJ34 PP08906,227,654 IJ35 PP0873 6,209,989 IJ36 PP0993 6,247,791 IJ37 PP08906,336,710 IJ38 PP1398 6,217,153 IJ39 PP2592 6,416,167 IJ40 PP25936,243,113 IJ41 PP3991 6,283,581 IJ42 PP3987 6,247,790 IJ43 PP39856,260,953 IJ44 PP3983 6,267,469 IJ45 PO7935 6,224,780 IJM01 PO79366,235,212 IJM02 PO7937 6,280,643 IJM03 PO8061 6,284,147 IJM04 PO80546,214,244 IJM05 PO8065 6,071,750 IJM06 PO8055 6,267,905 IJM07 PO80536,251,298 IJM08 PO8078 6,258,285 IJM09 PO7933 6,225,138 IJM10 PO79506,241,904 IJM11 PO7949 6,299,786 IJM12 PO8060 09/113,124 IJM13 PO80596,231,773 IJM14 PO8073 6,190,931 IJM15 PO8076 6,248,249 IJM16 PO807509/113,120 IJM17 PO8079 6,241,906 IJM18 PO8050 09/113,116 IJM19 PO80526,241,905 IJM20 PO7948 09/113,117 IJM21 PO7951 6,231,772 IJM22 PO80746,274,056 IJM23 PO7941 6,290,861 IJM24 PO8077 6,248,248 IJM25 PO80586,306,671 IJM26 PO8051 6,331,258 IJM27 PO8045 6,110,754 IJM28 PO79526,294,101 IJM29 PO8046 6,416,679 IJM30 PO9390 6,264,849 IJM31 PO93926,254,793 IJM32 PP0889 6,235,211 IJM35 PP0887 6,491,833 IJM36 PP08826,264,850 IJM37 PP0874 6,258,284 IJM38 PP1396 6,312,615 IJM39 PP39896,228,668 IJM40 PP2591 6,180,427 IJM41 PP3990 6,171,875 IJM42 PP39866,267,904 IJM43 PP3984 6,245,247 IJM44 PP3982 6,315,914 IJM45 PP08956,231,148 IR01 PP0870 09/113,106 IR02 PP0869 6,293,658 IR04 PP088709/113,104 IR05 PP0885 6,238,033 IR06 PP0884 6,312,070 IR10 PP08866,238,111 IR12 PP0871 09/113,086 IR13 PP0876 09/113,094 IR14 PP08776,378,970 IR16 PP0878 6,196,739 IR17 PP0879 09/112,774 IR18 PP08836,270,182 IR19 PP0880 6,152,619 IR20 PP0881 09/113,092 IR21 PO80066,087,638 MEMS02 PO8007 6,340,222 MEMS03 PO8008 09/113,062 MEMS04 PO80106,041,600 MEMS05 PO8011 6,299,300 MEMS06 PO7947 6,067,797 MEMS07 PO79446,286,935 MEMS09 PO7946 6,044,646 MEMS10 PO9393 09/113,065 MEMS11 PP087509/113,078 MEMS12 PP0894 6,382,769 MEMS13

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

FIELD OF THE INVENTION

The present invention relates to an ink jet printer device.

BACKGROUND OF THE INVENTION

Many different types of printing have been invented, a large number ofwhich are presently in use. The known forms of print have a variety ofmethods for marking the print media with a relevant marking media.Commonly used forms of printing include offset printing, laser printingand copying devices, dot matrix type impact printers, thermal paperprinters, film recorders, thermal wax printers, dye sublimation printersand ink jet printers both of the drop on demand and continuous flowtype. Each type of printer has its own advantages and problems whenconsidering cost, speed, quality, reliability, simplicity ofconstruction and operation etc.

In recent years, the field of ink jet printing, wherein each individualpixel of ink is derived from one or more ink nozzles has becomeincreasingly popular primarily due to its inexpensive and versatilenature.

Many different techniques of ink jet printing have been invented. For asurvey of the field, reference is made to an article by J Moore,“Non-Impact Printing: Introduction and Historical Perspective”, OutputHand Copy Device, Editors R Dubeck and S Sherr, pages 207-220 (1988).

Ink Jet printers themselves come in many different forms. Theutilization of a continuous stream of ink in ink jet printing appears todate back to at least 1929 wherein U.S. Pat. No. 1,941,001 by Hanselldiscloses a simple form of continuous stream electrostatic ink jetprinting.

U.S. Pat. No. 3,596,275 by Sweet also discloses a process of continuousink jet printing including a step wherein the ink jet stream ismodulated by a high frequency electro-static field so as to cause dropseparation. This technique is still utilized by several manufacturersincluding Elmjet and Scitex (see also U.S. Pat. No. 3,373,437 by Sweetet al).

Piezoelectric ink jet printers are also one form of commonly utilizedink jet printing device. Piezoelectric systems are disclosed by Kyseret. al. in U.S. Pat. No. 3,946,398 (1970) which utilizes a diaphragmmode of operation, by Zolten in U.S. Pat. No. 3,683,212 (1970) whichdiscloses a squeeze mode of operation of a piezoelectric crystal, Stemmein U.S. Pat. No. 3,747,120 (1972) discloses a bend mode of piezoelectricoperation, Howkins in U.S. Pat. No. 4,459,601 discloses a piezoelectricpush mode actuation of the ink jet stream and Fischbeck in U.S. Pat. No.4,584,590 which discloses a shear mode type of piezoelectric transducerelement.

Recently, thermal ink jet printing has become an extremely popular formof ink jet printing. The ink jet printing techniques include thosedisclosed by Endo et al in GB 2007162 (1979) and Vaught et al in U.S.Pat. No. 4,490,728. Both the aforementioned references disclose ink jetprinting techniques which rely upon the activation of an electrothermalactuator which results in the creation of a bubble in a constrictedspace, such as a nozzle, which thereby causes the ejection of ink froman aperture connected to the confined space onto a relevant print media.Printing devices utilizing the electro-thermal actuator are manufacturedby manufacturers such as Canon and Hewlett Packard.

As can be seen from the foregoing, many different types of printingtechnologies are available. Ideally, a printing technology should have anumber of desirable attributes. These include inexpensive constructionand operation, high speed operation, safe and continuous long termoperation etc. Each technology may have its own advantages anddisadvantages in the areas of cost, speed, quality, reliability, powerusage, simplicity of construction operation, durability and consumables.

It would be desirable to create a more compact and efficient inkjetprinter having an efficient and effective operation in addition to beingas compact as possible.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective cross-sectional view of a single ink jet nozzleconstructed in accordance with a preferred embodiment;

FIG. 2 is a close-up perspective cross-sectional view (portion A of FIG.1), of a single ink jet nozzle constructed in accordance with apreferred embodiment;

FIG. 3 is an exploded perspective view illustrating the construction ofa single ink jet nozzle in accordance with a preferred embodiment;

FIG. 4 provides a legend of the materials indicated in FIGS. 1 to 15;and

FIGS. 5 to 15 illustrate sectional views of the manufacturing steps inone form of construction of an ink jet printhead nozzle.

DESCRIPTION OF PREFERRED AND OTHER EMBODIMENTS

The ink jet designs shown here are suitable for a wide range of digitalprinting systems, from battery powered one-time use digital cameras,through to desktop and network printers, and through to commercialprinting systems

For ease of manufacture using standard process equipment, the print headis designed to be a monolithic CMOS chip with MEMS post processing. Fora general introduction to micro-electric mechanical systems (MEMS)reference is made to standard proceedings in this field including theproceedings of the SPIE (International Society for Optical Engineering),volumes 2642 and 2882 which contain the proceedings for recent advancesand conferences in this field.

For color photographic applications, the print head is 100 mm long, witha width which depends upon the ink jet type.

IJ02

In a preferred embodiment, an ink jet print head is made up of aplurality of nozzle chambers each having an ink ejection port. Ink isejected from the ink ejection port through the utilization of attractionbetween two parallel plates.

Turning initially to FIG. 1, there is illustrated a cross-sectional viewof a single nozzle arrangement 210 as constructed in accordance with apreferred embodiment. The nozzle arrangement 210 includes a nozzlechamber 211 in which is stored ink to be ejected out of an ink ejectionport 212. The nozzle arrangement 210 can be constructed on the top of asilicon wafer utilizing micro electro-mechanical systems constructiontechniques as will become more apparent hereinafter. The top of thenozzle plate also includes a series of regular spaced etchant holes,e.g. 213 which are provided for efficient sacrificial etching of lowerlayers of the nozzle arrangement 210 during construction. The size ofthe etchant holes 213 is signal enough that surface tensioncharacteristics inhibit ejection from the holes 213 during operation.

Ink is supplied to the nozzle chamber 211 via an ink supply channel,e.g. 215.

Turning now to FIG. 2, there is illustrated a cross-sectional view ofone side of the nozzle arrangement 210. A nozzle arrangement 210 isconstructed on a silicon wafer base 217 on top of which is firstconstructed a standard CMOS two level metal layer 218 which includes therequired drive and control circuitry for each nozzle arrangement. Thelayer 218, which includes two levels of aluminum, includes one level ofaluminum 219 being utilized as a bottom electrode plate. Other portions220 of this layer can comprise nitride passivation. On top of the layer219 there is provided a thin polytetrafluoroethylene (PTFE) layer 221.

Next, an air gap 227 is provided between the top and bottom layers. Thisis followed by a further PTFE layer 228 which forms part of the topplate 222. The two PTFE layers 221, 228 are provided so as to reducepossible stiction effects between the upper and lower plates. Next, atop aluminum electrode layer 230 is provided followed by a nitride layer(not shown) which provides structural integrity to the top electroplate. The layers 228-230 are fabricated so as to include a corrugatedportion 223 which concertinas upon movement of the top plate 222.

By placing a potential difference across the two aluminum layers 219 and230, the top plate 222 is attracted to bottom aluminum layer 219 therebyresulting in a movement of the top plate 222 towards the bottom plate219. This results in energy being stored in the concertinaed springarrangement 223 in addition to air passing out of the side air holes,e.g. 233 and the ink, being sucked into the nozzle chamber as a resultof the distortion of the meniscus over the ink ejection port 212 (FIG.1). Subsequently, the potential across the plates is eliminated therebycausing the concertinaed spring portion 223 to rapidly return the plate222 to its rest position. The rapid movement of the plate 222 causes theconsequential ejection of ink from the nozzle chamber via the inkejection port 212 (FIG. 1). Additionally, air flows in via air gap 233underneath the plate 222.

The ink jet nozzles of a preferred embodiment can be formed fromutilization of semi-conductor fabrication and MEMS techniques. Turningto FIG. 3, there is illustrated an exploded perspective view of thevarious layers in the final construction of a nozzle arrangement 210. Atthe lowest layer is the silicon wafer 217 upon which all otherprocessing steps take place. On top of the silicon layer 217 is the CMOScircuitry layer 218 which primarily comprises glass. On top of thislayer is a nitride passivation layer 220 which is primarily utilized topassivate and protect the lower glass layer from any sacrificial processthat may be utilized in the building up of subsequent layers. Next thereis provided the aluminum layer 219 which, in the alternative, can formpart of the lower CMOS glass layer 218. This layer 219 forms the bottomplate. Next, two PTFE layers 226, 228 are provided between which is laiddown a sacrificial layer, such as glass, which is subsequently etchedaway so as to release the plate 222 (FIG. 2). On top of the PTFE layer228 is laid down the aluminum layer 230 and a subsequent thicker nitridelayer (not shown) which provides structural support to the top electrodestopping it from sagging or deforming. After this comes the top nitridenozzle chamber layer 235 which forms the rest of the nozzle chamber andink supply channel. The layer 235 can be formed from the depositing andetching of a sacrificial layer and then depositing the nitride layer,etching the nozzle and etchant holes utilizing an appropriate maskbefore etching away the sacrificial material.

Obviously, print heads can be formed from large arrays of nozzlearrangements 210 on a single wafer which is subsequently diced intoseparate print heads. Ink supply can be either from the side of thewafer or through the wafer utilizing deep anisotropic etching systemssuch as high density low pressure plasma etching systems available fromsurface technology systems. Further, the corrugated portion 223 can beformed through the utilization of a half tone mask process.

One form of detailed manufacturing process which can be used tofabricate monolithic ink jet print heads operating in accordance withthe principles taught by the present embodiment can proceed utilizingthe following steps:

1. Using a double sided polished wafer 240, complete a 0.5 micron, onepoly, 2 metal CMOS process 242. This step is shown in FIG. 5. Forclarity, these diagrams may not be to scale, and may not represent across section though any single plane of the nozzle. FIG. 4 is a key torepresentations of various materials in these manufacturing diagrams,and those of other cross referenced ink jet configurations.

2. Etch the passivation layers 246 to expose the bottom electrode 244,formed of second level metal. This etch is performed using Mask 1. Thisstep is shown in FIG. 6.

3. Deposit 50 nm of PTFE or other highly hydrophobic material.

4. Deposit 0.5 microns of sacrificial material, e.g. polyimide 248.

5. Deposit 0.5 microns of (sacrificial) photosensitive polyimide.

6. Expose and develop the photosensitive polyimide using Mask 2. Thismask is a gray-scale mask which defines the concertina edge 250 of theupper electrode. The result of the etch is a series of triangular ridgesat the circumference of the electrode. This concertina edge is used toconvert tensile stress into bend strain, and thereby allow the upperelectrode to move when a voltage is applied across the electrodes. Thisstep is shown in FIG. 7.

7. Etch the polyimide and passivation layers using Mask 3, which exposesthe contacts for the upper electrode which are formed in second levelmetal.

8. Deposit 0.1 microns of tantalum 252, forming the upper electrode.

9. Deposit 0.5 microns of silicon nitride (Si₃N₄), which forms themovable membrane of the upper electrode.

10. Etch the nitride and tantalum using Mask 4. This mask defines theupper electrode, as well as the contacts to the upper electrode. Thisstep is shown in FIG. 8.

11. Deposit 12 microns of (sacrificial) photosensitive polyimide 254.

12. Expose and develop the photosensitive polyimide using Mask 5. Aproximity aligner can be used to obtain a large depth of focus, as theline-width for this step is greater than 2 microns, and can be 5 micronsor more. This mask defines the nozzle chamber walls. This step is shownin FIG. 9.

13. Deposit 3 microns of PECVD glass 256. This step is shown in FIG. 10.

14. Etch to a depth of 1 micron using Mask 6. This mask defines thenozzle rim 258. This step is shown in FIG. 11.

15. Etch down to the sacrificial layer 254 using Mask 7. This maskdefines the roof of the nozzle chamber, and the nozzle 260 itself. Thisstep is shown in FIG. 12.

16. Back-etch completely through die silicon wafer 246 (with, forexample, an ASE Advanced Silicon Etcher from Surface Technology Systems)using Mask 8. This mask defines the ink inlets 262 which are etchedthrough the wafer 240. The wafer 240 is also diced by this etch.

17. Back-etch through the CMOS oxide layer through the holes in thewafer 240. This step is shown in FIG. 13.

18. Etch the sacrificial polyimide 254. The nozzle chambers 264 arecleared, a gap is formed between the electrodes and the chips areseparated by this etch. To avoid stiction, a final rinse usingsupercooled carbon dioxide can be used. This step is shown in FIG. 14.

19. Mount the print heads in their packaging, which may be a moldedplastic former incorporating ink channels which supply the appropriatecolor ink to the ink inlets at the back of the wafer.

20. Connect the print heads to their interconnect systems. For a lowprofile connection with minimum disruption of airflow, TAB may be used.Wire bonding may also be used if the printer is to be operated withsufficient clearance to the paper.

21. Hydrophobize the front surface of the print heads.

22. Fill the completed print heads with ink 266 and test them. A fillednozzle is shown in FIG. 15.

The presently disclosed ink jet printing technology is potentiallysuited to a wide range of printing system including: color andmonochrome office printers, short run digital printers, high speeddigital printers, offset press supplemental printers, low cost scanningprinters high speed pagewidth printers, notebook computers with inbuiltpagewidth printers, portable color and monochrome printers, color andmonochrome copiers, color and monochrome facsimile machines, combinedprinter, facsimile and copying machines, label printers, large formatplotters, photograph copiers, printers for digital photographic“minilabs”, video printers, PHOTO CD (PHOTO CD is a registered trademarkof the Eastman Kodak Company) printers, portable printers for PDAs,wallpaper printers, indoor sign printers, billboard printers, fabricprinters, camera printers and fault tolerant commercial printer arrays.

It would be appreciated by a person skilled in the art that numerousvariations and/or modifications may be made to the present invention asshown in the specific embodiments without departing from the spirit orscope of the invention as broadly described. The present embodimentsare, therefore, to be considered in all respects to be illustrative andnot restrictive.

1. An ink jet printhead comprising: a silicon substrate; a CMOS layercomprising drive and control circuitry, said CMOS layer being formed onsaid silicon substrate; a passivation layer covering said CMOS layer;and a plurality of nozzles mounted on said passivation layer, eachnozzle comprising: a chamber adapted to contain an ejectable liquid;and, at least one droplet ejection actuator associated with each of thechambers respectively, the droplet ejection actuator being electricallyconnected to the drive circuitry and adapted to eject a droplet of theejectable liquid from the nozzle, wherein each chamber comprises a roofand sidewalls extending from said passivation layer to said roof,wherein said roof and said sidewalls are both comprised of a glassmaterial.
 2. An ink jet printhead according to claim 1, wherein theglass material is silicon nitride.
 3. An ink jet printhead according toclaim 1, wherein the printhead is a pagewidth printhead.
 4. An ink jetprinthead according to claim 1, wherein the glass material is depositedby plasma enhanced chemical vapor deposition (PECVD).